The ever-increasing demand for new biologically active chiral compounds, in particular pharmaceuticals and agrochemicals, continues to nurture tremendous interest in asymmetric synthesis.1 The development of enantioselective reactions for the production of chiral compounds is vigorously pursued at numerous academic and industrial research laboratories, and the pace and prospect of these efforts have increased significantly during the last 20 years with the introduction of combinatorial methods. In contrast, the analysis of the amount and enantiomeric composition of chiral compounds has become a major bottleneck in the discovery process.
High-throughput screening (HTS) methods capable of analyzing large numbers of samples that can be generated overnight are required to match the productivity of parallel synthesis and other combinatorial techniques. It has been proposed that optical methods based on fluorescence, UV and circular dichroism spectroscopy hold considerable promise toward the goal of enantioselective HTS.2 Several optical sensing assays developed to date have been found to outperform chromatographic and NMR spectroscopic methods with regard to time-efficiency, sensitivity and waste production.3-5 
Optical assays typically provide information on the enantiomeric excess but require independent analysis of the concentration of the substrate tested unless two chemosensors are used simultaneously or in tandem.6 Because a complete stereochemical analysis must reveal the absolute configuration, the enantiomeric composition, and the total concentration of a chiral compound, the development of a widely useful and practical probe that can accomplish all three tasks with high accuracy is a significant challenge in the field of organic chemistry. To become practical for HTS purposes, the processes described above have to occur within a few minutes and generate strong (chir)optical responses that can be accurately quantified.